We had a program in our school district, before budget cuts, called Junior 1st grade which was an interim between kindergarten and 1st grade.
Giving my son the extra year (his birthday is July 29th) was THE BEST thing we could have done for him. Not only in school but socially outside of school.
This has nothing to do with her intelligence it is maturity. Most states cut off is September 1st vs. December 1st for Michigan.
Let her be one of the older kids instead of the younger ones.
Think about this...Would you want a more mature 18 year old going to college or a young 17 year old going to college?
Also, she will make new friends and give her the extra year now and let friends and school work be easier instead of a struggle every year.
Now is the time to do it.
This obviously has nothing to do with your daughter's intelligence it is about her maturity. Give her the chance to be a confident strong girl. She will succeed!
There is nothing wrong with her. She is young. That's all.
There are many students in our school district who have had that extra year and are thriving.
I hope this helps and if you have any questions, I'm here to help.